hmm if all else fails, you could try my modified setup...
Quoted and little modified (x64 -> x86, but with added touch of x32 
why the typo? i realy dont know) from:
http://forums.logitech.com/logitech/board/message?
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--------------------------------- -Download and extract mattx's rar file (http://www.burukan.com/logitech/setpoint500_g9_x32
_mattx.rar) -Run mattx's msi (setpoint500_g9_x32_mattx.msi for me)
-This will install setpoint correctly but nothing else. Now what you need is to update windows's standard HID mouse drivers to Logitech's specific HID drivers for the g9 mouse.
-Open device manager. (Start --> Right click computer --> properties --> device manager)
-Under mice and other pointing devices, right click HID-compliant mouse and choose update driver software.
-Choose browse my computer for driver software, to install the driver manually.
-Point the folder to the one with extracted driver files in it (MouseDriver_x32)
-Click next, and hopefully it should update the driver to Logitech's g9 driver.
The key to this workaround is this:
-Well, of course, it is a workaround and requires work since setpoint is not supported on Vista/Server 2008.
-Setpoint does not want to install at all. Namely,
-Setpoint does not extract the files and run the actual software. This is solved by Mattx's msi.
-The mouse driver is not updated to the logietch version. This is required to have setpoint recognize it.
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I had originally done x64 and that is it seems very widely used (at least download logs says so). You can read the first page in that thread for more info. This one was created roughly same days (FTP file dated 9/4/2008) but not mentioned much. Let's see if it helps you fix your problem.
